The invention relates to a method and a device for the two-dimensional and three-dimensional bending of rod-shaped components, such as tubes and profiles, by a device comprising two roller systems A and B disposed behind each other along the longitudinal axis.
At present, machines being employed for the bending of tubes are, above all, mandrel bending machines (Franz, W.-D., Maschinelles Rohrbiegen. Verfahren and Maschinen. [Mechanical Tube Bending. Methods and Machines.], VDI-Verlag, ISBN 3-18-400814-2, 1988). In order to perform 3D bending of a tube in these machines, the tube to be bent is turned by twisting the tube cross-section, and is thereby moved into another bending plane, in which bending is then continued. This change from one bending plane to another results in 3D contours. However, this enables only invariable radii that are predetermined by the bending tool. Furthermore, with such machines it is not possible to produce 3D bends in profiles since when bending a profile, the required tool cross-section changes when the bending plane is changed, unlike with tubes having a circular cross-section.
Furthermore, so-called “free-formers” are known, which are likewise utilized only for tubes and are frequently built into mandrel bending machines as special tools (Rasi Maschinenbau GmbH., Alles unter Kontrolle beim Rohrbiegen. Blech Rohre Profile [Everything under Control with Tube Bending. Sheet Metal Tube Profiles], p. 40 ff (09.2002)). These “free-formers” operate according to the principle of roll forming, wherein the tubes are guided between at least 3 rolls in a plane. To change the bending plane, the tube must first be twisted between the rolls. Here again, the circular cross-section of tubes is very helpful. Using this principle, it is not possible to spatially bend non-circular profiles, since these get jammed in the bending rolls.
Furthermore, free-form bending machines have become known in recent years that work with sliding guides (Neugebauer R.; Blau P.; Drossel W-G., 3D-Freiformbiegen von Profilen. [3D-Free-Form Bending of Profiles], ZWG, Nov. 12, 2001). Here, the tube or profile is pushed through corresponding guide bushes, which are offset relative to each other and which bend the profile in the process. A disadvantage here is that an additional, strong pusher is required and that the occurring large friction forces may damage the surface of the tube or profile. For this reason, as a rule, lubricants are being utilized in these machines, which have to be laboriously removed from the workpiece after the working. An additional disadvantage is that fitting bushes need to be manufactured for each type of profile, which bushes, due to the high contact pressures per unit area, consist of expensive ceramic materials. In these free-form bending machines, the spatial direction in which the profile emerges from the machine is always dependent on the contour of the bent component. For this reason, complex multi-axis kinematics of the guide bushes is necessary in order to exactly reproduce the spatial curve of the bent component at that location, making such a free-form bending machine very complex and expensive. In addition, if it is desired to measure the profile during the process at the outlet of the machine (e.g., for control purposes) this will require a complex sensor system that is capable of recording 3D coordinates.
All systems that are currently being used utilize a relatively complex pusher that pushes the profile positively via the longitudinal axis. Here, the profile has to be guided in a relatively elaborate manner to prevent the profile from buckling induced by the thrust load. This is furthermore disadvantageous because the pusher puts a limit on the total length of the tubes and profiles that can be worked.